For Big Ten I would guess for the 3 fixed rivals
With USC and NW both being private schools in large metro areas, they could be considered rivals, right?
USC - UCLA, Wisc, NW
UCLA - USC, Mich, Neb
NEB- Iowa, Minn, UCLA
Iowa - NEB, Minn, Wisc
Minn - Wisc, NEB, Iowa
Wisc - Minn, Iowa, USC
NW - ILL, Pur, USC
ILL - NW, Indy, Pur
Pur - Indy, NW, ILL
Indy - Pur, ILL, MSU
Mich - OSU, MSU, UCLA
MSU - Mich, Indy, MD
OSU - Mich, PSU, Rut
PSU - OSU, MD, Rut
MD - Rut, PSU, MSU
Rut - MD, PSU, OSU